Strip-type segment and laminated stator core for an electrical machine

ABSTRACT

A striplike lamination ( 10 ) for a stator of an electrical machine is proposed, in which the striplike lamination has an end contour ( 19 ) on each strip end ( 18 ). The end contours ( 19 ) are embodied such that a difference in length at the lamination ( 10 ) resulting from bending can be compensated for.

PRIOR ART

[0001] The invention relates to a striplike lamination for a stator ofan electrical machine and to a stator lamination packet made of suchstriplike laminations. From German Patent Disclosure DE-OS 26 295 32, astator for an electrical machine is already known which is made from aniron packet that is initially present in flat form. To produce it,striplike laminations provided with slots are disposed such that theyform a flat lamination packet. All the slots of the individuallaminations are oriented in the same direction, resulting in an overallcomblike arrangement of this packet. This flat packet is hereinaftercalled a flat packet. In the aforementioned patent disclosure, this flatpacket is bent into a round shape in a further step in such a way that astator lamination packet is obtained which can be used like conventionalannular stator lamination packets. This reference already describes thefact that after the flat packet has been bent into a round shape, thetwo ends facing one another of the laminations are separated by a slightspacing. To join these two ends together, it is provided that they bejoined together by welding, using a coating metal. This embodiment hastwo disadvantages. First, a coating metal must additionally be applied,which on the one hand involves cost and on the other requires majorexpenditure of energy, on the one hand to melt it and on the other tojoin this coating metal to the two ends. A further disadvantage is thatthis coating metal creates a relatively large nonlaminated cross sectionin the axial direction of the stator. Because there are increased eddycurrents in the cross section of the stator, this increases thecorresponding eddy current losses. Moreover, the application weldingintroduces a relatively large amount of energy into the stator.Furthermore, the gap mentioned in the prior art between the two endsleads to poorer efficiency at that point.

ADVANTAGES OF THE INVENTION

[0002] The striplike lamination according to the invention for a statorof an electrical machine, having the characteristics of the main claim,has the advantage that the altered end contour compensates for adifference in length of the lamination caused by bending, so thatbetween the two ends, after the bending into a round shape, there is nolonger any spacing between the end faces, or ends. The two ends can thenbe joined without application welding. This has the advantage that nofurther material has to be melted. The energy input is less, and anespecially economical welding method can be employed. Laser welding isespecially suitable, as an example.

[0003] By the provisions recited in the dependent claims, advantageousrefinements of the striplike lamination of the main claim are possible.If the lamination has a yoke region with a neutral bending line, and theyoke region on the side remote from the teeth, on the far side of theneutral bending line, is longer than the neutral line, then therequirement for a joining operation at the two ends without aninterstice can be accomplished on the outside of the stator. The outercircumference of the stator is round and closed and can be joined bymeans of the laser welding process already mentioned.

[0004] It is furthermore provided that in the yoke region between theneutral bending line and the side of the yoke toward the teeth, the yokeregion is shorter than the bending line. By this provision, overall, aninterstice between the outside of the yoke and the inside of the yoke,or the two ends, is avoided.

[0005] Overall, there are various possibilities for compensation at theends of the lamination; a further possibility is to embody thelamination as concave on one end and convex on its other end, so thatthe two shapes first supplement one another in compensatory fashion, inthe sense of being without gaps, and on the other lead to a positiveengagement, which reinforces the bond between the two ends.

[0006] A stator lamination packet for an electrical machine is alsoprovided, in which the stator lamination packet is produced fromlaminations of one of the foregoing claims. A stator lamination packetof this kind has especially good roundness and is thus especially simpleto insert into bearing plates made round on a lathe.

DRAWING

[0007] In the drawings, exemplary embodiments of a striplike laminationof the invention, a stator lamination packet, and a correspondingelectrical machine are shown. Shown are:

[0008]FIG. 1, a striplike lamination for a stator, in a side view;

[0009]FIG. 2, a fragmentary view of the end region of a striplikelamination in a second exemplary embodiment;

[0010]FIG. 3 again shows the end region of a striplike lamination in athird exemplary embodiment;

[0011]FIG. 4 is a fragmentary view of a stator made of striplikelaminations of the invention;

[0012]FIG. 5 symbolically shows an electrical machine with a statorproduced from striplike laminations of the invention;

[0013]FIG. 6 shows a striplike lamination of the prior art;

[0014]FIG. 7 is a fragmentary view of the joining point before weldingin the prior art.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0015] In FIG. 1, a striplike lamination 10 of the invention is shown.The lamination 10 comprises a yoke region 12 and teeth 14 that areintegrally joined to this yoke region 12. The teeth 14 and the yokeregion 12 are in the same plane. The lamination 10, as in the prior artdescribed at the outset, is intended to be bent in its plane. The yokeregion 12 takes the form of a circular ring, as is known from statorsmade from annular laminations. In this intended bending in the plane ofthe yoke region 12 and the teeth 14, the teeth 14 are oriented radiallyinward. Inside the yoke region 12, the bending produces what is usuallycalled a “neutral fiber” bending line, which results approximately inthe middle of the yoke region 12 and here is called the neutral bendingline 16. This neutral bending line corresponds to the zone or line, in amaterial that is to be bent or that has been bent, in which neithertensile nor compressive stress prevails.

[0016] The lamination 10 has two ends 18, each with an end contour 19,which extends over the yoke region 12 and one end tooth 21 each. Bothend teeth 21 are embodied such that together they form one tooth, whichin its action is equivalent to one complete tooth 14. One part of theend contour 19 defines the two end teeth 21. This part of the endcontour 19 is not oriented perpendicular to the neutral bending line 16;instead, this part of the end contour 19 forms an angle that is greaterthan 90° with the bending line 16. Thus in contrast to the teeth 14, thetwo end teeth 21 are slightly spread apart from the yoke region 12. Theslots between each end tooth 21 and a respective adjacent tooth 14 arelarger than the slots between each two immediately adjacent teeth 14.

[0017] In the stretched-out original state of the striplike lamination,at least three different dimensions can be seen in the yoke region 12.The dimension l_(a) can be found on the side of the yoke region 12remote from the teeth 14, or in other words on the later outercircumference of the stator. In the region of the neutral bending line16, that is, approximately in the middle of the yoke region 12, lengthl_(n) of the neutral bending line 16 can be ascertained. On the laterinside circumference of the yoke region 12 as well, that is, preciselyat the point where the teeth 14 merge with the yoke region 12, ameasurement can be made. This length is called l_(z).

[0018] For the lengths l_(a), l_(n) and l_(z), on the condition that asa result of the end contour 19, a difference in length at the lamination10 resulting from bending can be compensated for, the followingconditions apply:

[0019] The length l_(a) must be greater than the line l_(n) of theneutral bending line 16. Thus the lamination 10 has a yoke region 12with a neutral bending line 16, which yoke region, on the side of theyoke region 12 remote from the teeth 14, on the far side of the neutralbending line 16, is longer than the neutral bending line 16.

[0020] Another desired condition is that l_(z) is less than l_(n). Thisformulation means the same as the condition that the lamination 10 has ayoke region 12 with a neutral bending line 16, and the yoke region onthe side toward the teeth 14, on the far side of the neutral bendingline 16, is shorter than the neutral bending line 16. The end teeth 21,with one side, likewise form one part of the end contour 19. In the viewin FIG. 1, it is provided that the two end contours 19 together with theend teeth 21 form one concave end contour 19. In the example of FIG. 1,it is shown that the transition of the end contour between the yokeregion 12 and the end tooth 21 is not smoothed but instead is pointed.

[0021]FIG. 2 shows a variant of an end contour 19. In a distinction fromthe exemplary embodiment of FIG. 1, the end contour 19 in the exemplaryembodiment of FIG. 2 has a course without a kink, so that although theformulated relationships with regard to l_(a), l_(n) and l_(z) stillhave validity, nevertheless the end contour 19 extends essentially in astraight line, and thus the end tooth 21 is somewhat narrower than inFIG. 1. The dashed line in FIG. 2 shows the contour 19 in the prior art.

[0022] In FIG. 3, a further exemplary embodiment for a lamination 10 isshown. Here, the two end contours 19 of the lamination 10 are locatedfacing one another. This makes their cooperation clear. Here, thelamination 10 has a concave end contour 19 on one end 18 and a convexend contour 19 on its other end. Once again, both end contours 19 areshaped such that a difference in length at the lamination caused bybending can be compensated for. Furthermore, embodying the two ends witha concave and convex form respectively means that a certain positiveengagement is made possible.

[0023] In FIG. 4, a stator lamination packet 23 is shown. In particular,the joining point 22 at which the ends 18 of the laminations 10 arejoined together is shown. The stator lamination packet 23 comprises acertain number of initially striplike laminations 10, which as in theprior art are bent into a round stator iron in such a way that the teeth14 point radially inward. The laminations 10 of the stator laminationpacket 23 are produced in accordance with one of the exemplaryembodiments described above for the striplike laminations 10.

[0024] In FIG. 5, an electrical machine 25 with a stator laminationpacket 23 of FIG. 4 is shown. This illustration is symbolic. The statorlamination packet 23 has a winding, not shown, and with it forms astator, which is intended for interaction with a rotor, not shown. It isprovided that the winding be inserted, and in the stretched-out, flatstate of the lamination packet, into the slots between the teeth 14 andend teeth 21. Moreover, a stator lamination packet produced in this wayis also suitable for windings that are inserted into the slots by theknown drawing-in technique.

[0025]FIG. 6 shows a conventional striplike lamination 10 known from theprior art, in which the ends 18 are not shaped in such a way that theycompensate for a difference in length at the lamination 10 caused bybending.

[0026] In FIG. 7, the effect of the bending of such conventionalstriplike laminations 10 into a round shape is shown. It can be seenclearly that at the joining point 22, a gap is created on thecircumference of the stator iron 23.

1. A striplike lamination for a stator of an electrical machine, havingone end contour (19) on each strip end (18), characterized in that bymeans of the end contour (19), a difference in length at the lamination(10) caused by bending can be compensated for.
 2. The striplikelamination of claim 1, characterized in that the lamination (10) has ayoke region (12) with a neutral bending line (16), which on the sidefacing away from teeth (14), on the far side of the neutral bending line(16), is longer than the neutral bending line (16).
 3. The striplikelamination of claim 1, characterized in that the lamination (10) has ayoke region (12) with a neutral bending line (16), which on the sidefacing toward teeth (14), on the far side of the neutral bending line(16), is shorter than the neutral bending line (16).
 4. The striplikelamination of claim 1, characterized in that the lamination (10) isembodied as concave on one end and convex on another end.
 5. A statorlamination packet for an electrical machine, characterized in that it isproduced from laminations (10) of claim
 1. 6. An electrical machinehaving a stator lamination packet of claim 5.